Method of forming rectangular cross section foam polyurethane by directing upward currents of air along the sides of the forming trough

ABSTRACT

A continuous slab of rectangular cross-sectional outline is formed by feeding free-rising polyurethane foam into a trough formed by travelling bottom and lateral liners of release paper so that such foam forms a continuous loaf which travels lengthwise through a foaming zone wherein it rises to form the slab. Friction between lateral liners and the sides of the loaf is reduced by currents of gas which are blown upwardly along the edges of the bottom liner.

United States Patent [72] inventor Werner Hagen Unterpiaffenhofen nearMunich, Germany [2 1] Appl. No. 754,078 [22] Filed Aug. 20, 1968 [45]Patented Dec. 14, 1971 [73] .Assignee Metzeller AG Munich, Germany [32]Priority Aug. 21, 1967 [33] Germany [31 P 17 04 846.3

[5 METHOD OF FORMING RECTANGULAR CROSS- SECTION FOAM POLYURETHANE BYDIRECTING UPWARD CURRENTS OF AIR ALONG THE SIDES OF THE FORMING TROUGH 8Claims, 5 Drawing Figs.

[52] U.S. Cl 264/51, 18/4 B, 18/5 A, 18/5 P, 264/54, 264/88 [51 int. Cl829d 27/04 [50] Field of Search 264/54, 88,

[56] References Cited UNITED STATES PATENTS 3,152,361 10/1964 Edwards264/54 X 3,193,406 7/1965 Mittelman 264/88 X 3,197,531 7/1965 WilburPrimary ExaminerDonald .1. Arnold Assistant Examiner- Paul A. LeipoldAttorney-Michael S. Striker ABSTRACT: A continuous'slab of rectangularcross-sectional outline is formed by feeding fre e-rising polyurethanefoam into a trough formed by travelling bottom and lateral liners ofrelease paper so that such foam forms a continuous loaf which travelslengthwise through a foaming zone wherein it rises to form the slab.Friction between lateral liners and the sides of the loaf is reduced bycurrents of gas which are.blown upwardly along the edgesof the bottomliner.

PATENIEBIEMMY. f I

saw 1 or 2 Invenlor: V Werner Huge NsAIlornqy f PAW-m 4m:

SHEET 2 OF 2 Fig. 1

f Inventor:

his Attorney METHOD OF FORMING RECTANGULAR CROSS: SECTION FOAMPOLYURETHANE BY DIRECTING UPWARD CURRENTS OF AIR ALONG THE SIDES OF THEFORMING TROUGH CROSS-REFERENCE TO RELATED APPLICATION BACKGROUND OF THEINVENTION The present invention relates to a method and apparatus forthe production of foam material. More particularly, the inventionrelates to a method and apparatus for the production of slabs consistingof flexible urethane stock or analogous synthetic plastic material.Still more particularly the invention relates to continuous productionof slabs which are obtained on foaming of free-rising foam which travelslengthwise within the confines of a liner of release paper or the likeand which is controlled while it rises to form a slab of substantiallyor exactly rectangular cross-sectional outline.

Slabs with a substantially rectangular cross-sectional outline arepresently produced in a stationary mold which accommodates a travellingflexible liner of release paper serving to advance free-rising foamthrough a foaming zone wherein the material rises to form a slab. Suchtraveling liner coats the bottom wall of the trough. Two lateral linersare provided along the inner sides of the sidewalls of the trough andare caused to perform a composite movement having a horizontal componentin the direction of travel of the loaf-supporting liner and an upwardlyoriented vertical component. Such composite movements of lateral linersare intended to insure that the sides of the loaf rise at the same rateas the central portion thereof so that the resulting slab does notexhibit a pronounced ridge or crest. The lower edge portions of thelateral liners are caused to overlie a substantially runnerlike guideplate which extends from the point where the loaf begins to foam. Thespeed of horizontal movement of lateral liners equals the forward speedof the bottom liner and their speed in the direction upwardly and awayfrom the bottom liner is such that it at least equals or even exceedsthe speed at which the loaf rises during travel through the foamingzone. This is intended to reduce friction between the loaf and thelateral liners and to thus insure free rise of the loaf and theformation of a flat-top slab. Reference may be had to German Pat. No.1,207,072.

A drawback of the just outlined procedure is that the speed of travel oflateral liners must be controlled with a high-degree of precision andthat the foaming zone must be supervised at all times in order to insurethat the vertical component of movement of each lateral linercorresponds to the speed at which the loaf rises. The problem is thesame in certain other types of conventional apparatus wherein thelateral liners are replaced by rotating disks which flank the foamingzone. The speed of such disks must be controlled with a high degree ofprecision which involves the use of skilled labor and complicatedadjusting and detecting mechanisms.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a novel and improved method of producing flat-top slabs offoamed material.

Another object of the invention is to provide a method according towhich a loaf of free-rising foam can be converted into a slab ofrectangular cross-sectional outline without necessitating constantsupervision of the foaming zone and/or transport of release paper inseveral directions.

A further object of the invention is to provide a novel method ofreducing friction between a travelling loaf of rising foam and liners ofrelease paper.

An additional object of this invention is to provide an apparatus whichcan be employed in the practice of the aboveoutlined method.

An ancillary object of the invention is to provide the ap paratus withnovel means for reducing or eliminating friction between a travellingloaf of free-rising foam and lateral liners of release paper.

The improved method comprises the steps of feeding freerising foam intoan elongated path to form a continuous loaf which is confined from belowand at two sides thereof, advancing the load lengthwise through afoaming zone wherein the loaf rises to form a slab, and establishingupwardly flowing current of air or another suitable gas at both sides ofthe loaf in the foaming zone.

The path for the loaf is preferably horizontal or nearly horizontal. Thespeed of the upwardly flowing current at one side of the loaf ispreferably the same as the speed of the other current. Both currentspreferably flow vertically upwardly.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved apparatus itself, however, both as to its construction and itsmode of operation, together with additional features and advantagesthereof, will be best understood upon perusal of the following detaileddescription of a specific embodiment with reference to the accompanyingdrawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary schematiclongitudinal vertical sectional view of an apparatus which embodies theinvention;

FIG. 2 is a transverse vertical sectional view as seen in the directionof arrows from the line II-II of FIG. 1;

FIG. 3 is a section on the line III--III of FIG. 1;

FIG. 4 is a section on the line IV-IV of FIG. I; and

FIG. Sis a section on the line V-V of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1 and 2 illustrate anelongated conveyor 1 having a travelling bottom portion including abottom wall 3 and a bottom liner 4 of release paper or the like whichoverlies the bottom wall. The conveyor further comprises two stationarysidewalls 2 which extend upwardly from the bottom wall 3 and areseparated therefrom by narrow clearances or gaps 6. Those sides of thesidewalls 2 which face each other are coated with lateral liners 4a ofrelease paper or the like. As shown in FIG. 2, the marginal portions 5of the bottom liner 4 are turned upwardly so that this bottom linerforms a shallow trough which receives a continuous supply of free-risingfoam from a feed F shown in FIG. 1. This feed may include a source offree-rising foam and a customary traversing head which movestransversely of the bottom wall 3 and discharges foam which forms acontinuous loaf 9. Such loaf is then advanced with the bottom liner 4through an elongated foaming zone 7 where it rises to form a slab 9a(FIGS. 1 and 5). The point or area where the traversing head of the feedF admits free-rising foam is indicated at 8.

The gaps extend along the fulllength of the foaming zone 7 and serve toadmit ascending currents of air or other gas. The means for establishingsuch currents of gas includes a pair of elongated pipes 11 havingorifices which discharge gas into the respective gaps. The pipes l 1 areconnected to a source 12 of compressed gas, for example, to an aircompressor or a pressure tank.

The operation is as follows:

The feed F admits free-rising foam at 8 whereby such foam spreads on thebottom liner 4 between the marginal portions 5 and forms a continuousloaf 9 which advances lengthwise through the foaming zone 7. Theintermediate stages in rise of the loaf 9 are shown in FIGS. 3 and 4. Atthe downstream end of the foaming zone 7, the loaf 9 is fully convertedinto a slab 9a (FIG. 5) which is a flat-top slab, i.e., it does notexhibit a crest or ridge which nonnally extends along the center of thetop surface of a conventional slab. The pipes 11 admit compressed gaswhile successive increments of the loaf 9 advance through the foamingzone 7 whereby the resulting currents of gas eliminate or reducefriction between the sides of the loaf and the lateral liners 4a so thatthe sides of the loaf can rise at the same rate as its central zone.

If desired, the lateral liners 4a can form with the bottom liner 4 anintegral liner which resembles a trough having rows of perforationsextending along the sides of the bottom wall 3. Such perforations mayresemble the perforations of roll film and serve to admit currents ofgas issuing from the orifices of the pipes 11. The perforations may beformed in the lower marginal portions of lateral liners 40 and/or in themarginal portions 5 of the bottom lines 4.

An important advantage of my improved method and apparatus is that it isnot necessary to continuously inspect the foaming zone 7, i.e., tomonitor the rate at which the loaf 9 rises in the region between thefeed F and the downstream end of the foaming zone. All that is necessaryis to properly select the speed at which the currents of air flowupwardly along the inner sides of the lateral liners 4a and to thereuponmaintain such speed until and unless the composition of free-risingmaterial issuing from the feed F is changed. The appropriate speed ofgas flow can be readily determined by simple experimentation. The liners4a preferably travel with the liner 4 even though it is also possible toemploy stationary lateral liners. The speed of both gas currents ispreferably the same and each of the pipes 11 preferably discharges aline or row of vertical jets of gas.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:

1. A method of producing foamed slabs of substantially rectangularcross-sectional outline, comprising the steps of providing an upwardlyopen elongated trough defined by a longitudinally travelling bottomportion and sidewalls extending upwardly from said bottom portion atopposite lateral sides of but out of contact with the same; feedingfree-rising synthetic plastic polyurethane foam into said trough so asto form in the latter a continuous loaf which is confined from below andat opposite lateral sides; advancing the loaf longitudinally of saidtrough on said travelling bottom portion while the loaf rises to from aslab; and directing currents of gas in upward flow between therespective lateral sides of the rising loaf and the respective sidewallsto thereby reduce friction between them.

2. A method as defined in claim 1, and further comprising the step ofinterposing a flexible liner between said bottom portion and said loaf.

3. A method as defined in claim 1, an comprising the step of maintainingsaid sidewalls stationary with reference to said loaf and said bottomportion.

4. A method as defined in claim I, and further comprising the step ofinterposing flexible liners between said loaf and the respectivesidewalls outwardly of said currents.

5. A method as defined in claim 1, wherein said gas is air.

6. A method as defined in claim 1, wherein said trough is substantiallyhorizontal.

7. A method as defined in claim 1, where the speed of the currents atboth sides of the loaf is the same.

8. A method as defined in claim 1, wherein the directions of gas flow atboth sides of the loaf are vertical.

2. A method as defined in claim 1, and further comprising the step ofinterposing a flexible liner between said bottom portion and said loaf.3. A method as defined in claim 1, and comprising the step ofmaintaining said sidewalls stationary with reference to said loaf andsaid bottom portion.
 4. A method as defined in claim 1, and furthercomprising the step of interposing flexible liners between said loaf andtHe respective sidewalls outwardly of said currents.
 5. A method asdefined in claim 1, wherein said gas is air.
 6. A method as defined inclaim 1, wherein said trough is substantially horizontal.
 7. A method asdefined in claim 1, where the speed of the currents at both sides of theloaf is the same.
 8. A method as defined in claim 1, wherein thedirections of gas flow at both sides of the loaf are vertical.